1. Field of the Invention
The present invention pertains generally to the characterization of multimedia traffic sources and more particularly to a method of determining loss curves for multimedia traffic sources utilized within a packet network environment.
2. Description of the Background Art
The explosive growth of the Internet has spawned a number of video-based services which operate over packet networks, such as streaming video and video-on-demand. These applications often require, or can benefit from, an ability to provide Quality-of-Service (QoS) guarantees for the network. The QoS guarantees are usually in the form of bandwidth, end-to-end delay, and/or the loss rate experienced by the traffic stream. The rate variability of these video sources has introduced the need for characterizing the associated traffic so that resources within the network, such as bandwidth and buffer space, may be properly allocated during the call admission control (CAC) process. Traffic characterization also allows for the efficient policing of the traffic sources. Two of the primary resources allocated within the network are the transmission rate ρ and the buffer size B. In an application where no losses are allowed, the video source can be characterized completely by determining the minimum buffer size necessary to avoid losses as a function of the rate ρ, and is referred to as the burstiness curve.
If the application can tolerate some amount of loss, the amount of bandwidth and/or buffer space required within the network can often be reduced significantly, since the burstiness curve of the source typically exhibits a long tail. The problem of determining the amount of network resources to allocate then becomes the problem of choosing a specific vector from the three-dimensional space (ρ, B,ε). In order to simplify the problem, either the transmission rate ρ or the buffer size B can be fixed and the corresponding curves calculated. The ε versus B curve for a specific video source transmission rate ρ enables the estimation of the loss rate resulting from a given buffer size. A plot of the loss rate as a function of the buffer size for a given rate ρ is referred to as the loss curve of the associated source at the given rate ρ.